package cn.ryh.netty.nio;


import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

/**
 * 使用 NIO 完成网络通信的三个核心：
 * 1.通道（Channel）：负责连接
 * 2. 缓冲区（Buffer）：负责数据的存取
 * 3. 选择器（Selector）：是 SelectableChannel 的多路复用器。用于监控 SelectableChannel 的 IO 状况
 */
public class SocketChannelDemo {

    public void client() throws IOException {
        SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1",9999));
        FileChannel inChannel = FileChannel.open(Paths.get("D:/1.jpg"), StandardOpenOption.READ);
        ByteBuffer buf = ByteBuffer.allocate(1024);

        //读取本地文件,发送到服务端
        while (inChannel.read(buf) != -1){
            buf.flip();
            sChannel.write(buf);
            buf.clear();
        }

        sChannel.shutdownOutput();

        //接收服务端的反馈
        int len = 0;
        while ((len = sChannel.read(buf)) != -1){
            buf.flip();
            System.out.println(new String(buf.array(),0,len));
            buf.clear();
        }

        inChannel.close();
        sChannel.close();
    }

    public void server() throws IOException {
        ServerSocketChannel ssChannel = ServerSocketChannel.open();
        FileChannel outChannel = FileChannel.open(Paths.get("D:/2.jpg"),StandardOpenOption.WRITE,StandardOpenOption.CREATE);

        //绑定端口号
        ssChannel.bind(new InetSocketAddress(9999));
        //获取客户端连接的通道
        SocketChannel sChannel = ssChannel.accept();

        ByteBuffer buf = ByteBuffer.allocate(1024);
        //接收客户端的数据,并保存到本地
        while (sChannel.read(buf) != -1){
            buf.flip();
            outChannel.write(buf);
            buf.clear();
        }

        //发送反馈给客户端
        buf.put("服务端接收数据成功!".getBytes());
        buf.flip();
        sChannel.write(buf);

        sChannel.close();
        outChannel.close();
        ssChannel.close();
    }
}
